[PATCH v4 0/3] Tegra GPCDMA: dma-channel-mask support

[PATCH v4 0/3] Tegra GPCDMA: dma-channel-mask support

[Akhil R]

Read dma-channel-mask from device tree and register only the
specified channels. This is useful to reserve some channels for the
firmware.

Also update the channel number and interrupts to include all 32
channels. The current DT bindings has only 31 interrupts which is wrong
and doesn't align with the hardware. This was done to reserve channel0
for the firmware. Now with this change, the driver can align more to the
actual hardware. but this implies that there will be a breakage in the
ABI and device tree must be updated along with the driver change
for it to pickup the right interrupt corresponding to the channel.

This breakage is okay right now because GPC DMA was introduced on
Tegra186 and the DT bindings were added in 5.19. Any products released
with this IP were released with kernels prior to 5.19 and bindings that
were never in-tree. Any of those products that are supported upstream we
know have replaceable DTB images (i.e. by default they are flashed at the
same time as the kernel image).


v3->v4:
  * Reverted back to v2 based on the discussion in the thread
    https://lore.kernel.org/all/Y2EFoG1H9YpfxRjs@orome/
  * Added description of the ABI breakage
v2->v3:
  * Updates in driver and DT to provide only the interrupts
    corresponding to the channels used in kernel. This would fix
    the ABI breakage that could occur with the previous version
v1->v2:
  * Reversed the operands and used BIT macro in 'if' condition.
  * Fixed warning reported-by: kernel test robot <lkp@intel.com>

Akhil R (3):
  dt-bindings: dmaengine: Add dma-channel-mask to Tegra GPCDMA
  arm64: tegra: Add dma-channel-mask in GPCDMA node
  dmaengine: tegra: Add support for dma-channel-mask

 .../bindings/dma/nvidia,tegra186-gpc-dma.yaml |  7 +++-
 arch/arm64/boot/dts/nvidia/tegra186.dtsi      |  4 +-
 arch/arm64/boot/dts/nvidia/tegra194.dtsi      |  4 +-
 arch/arm64/boot/dts/nvidia/tegra234.dtsi      |  4 +-
 drivers/dma/tegra186-gpc-dma.c                | 37 +++++++++++++++----
 5 files changed, 45 insertions(+), 11 deletions(-)

-- 
2.17.1

[PATCH v4 1/3] dt-bindings: dmaengine: Add dma-channel-mask to Tegra GPCDMA

[Akhil R]

Add dma-channel-mask property in Tegra GPCDMA document.

The property would help to specify the channels to be used in
kernel and reserve few for the firmware. This was previously
achieved by limiting the channel number to 31 in the driver.
This is wrong and does not align with the hardware. Correct
this and set the max interrupts to 32.

Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
---
 .../devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml   | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml b/Documentation/devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml
index c8894476b6ab..851bd50ee67f 100644
--- a/Documentation/devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml
+++ b/Documentation/devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml
@@ -39,7 +39,7 @@ properties:
       Should contain all of the per-channel DMA interrupts in
       ascending order with respect to the DMA channel index.
     minItems: 1
-    maxItems: 31
+    maxItems: 32
 
   resets:
     maxItems: 1
@@ -52,6 +52,9 @@ properties:
 
   dma-coherent: true
 
+  dma-channel-mask:
+    maxItems: 1
+
 required:
   - compatible
   - reg
@@ -60,6 +63,7 @@ required:
   - reset-names
   - "#dma-cells"
   - iommus
+  - dma-channel-mask
 
 additionalProperties: false
 
@@ -108,5 +112,6 @@ examples:
         #dma-cells = <1>;
         iommus = <&smmu TEGRA186_SID_GPCDMA_0>;
         dma-coherent;
+        dma-channel-mask = <0xfffffffe>;
     };
 ...
-- 
2.17.1

[PATCH v4 2/3] arm64: tegra: Add dma-channel-mask in GPCDMA node

[Akhil R]

Add dma-channel-mask property in Tegra GPCDMA device tree node.

The property would help to specify the channels to be used in
kernel and reserve few for the firmware. This was previously
achieved by limiting the channel number to 31 in the driver.
This is wrong and does not align with the hardware. Correct this
and update the interrupts property to list all 32 interrupts.

Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
---
 arch/arm64/boot/dts/nvidia/tegra186.dtsi | 4 +++-
 arch/arm64/boot/dts/nvidia/tegra194.dtsi | 4 +++-
 arch/arm64/boot/dts/nvidia/tegra234.dtsi | 4 +++-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/boot/dts/nvidia/tegra186.dtsi b/arch/arm64/boot/dts/nvidia/tegra186.dtsi
index 6602fe421ee8..db479064ff72 100644
--- a/arch/arm64/boot/dts/nvidia/tegra186.dtsi
+++ b/arch/arm64/boot/dts/nvidia/tegra186.dtsi
@@ -78,7 +78,8 @@
 		reg = <0x0 0x2600000 0x0 0x210000>;
 		resets = <&bpmp TEGRA186_RESET_GPCDMA>;
 		reset-names = "gpcdma";
-		interrupts = <GIC_SPI 76 IRQ_TYPE_LEVEL_HIGH>,
+		interrupts = <GIC_SPI 75 IRQ_TYPE_LEVEL_HIGH>,
+			     <GIC_SPI 76 IRQ_TYPE_LEVEL_HIGH>,
 			     <GIC_SPI 77 IRQ_TYPE_LEVEL_HIGH>,
 			     <GIC_SPI 78 IRQ_TYPE_LEVEL_HIGH>,
 			     <GIC_SPI 79 IRQ_TYPE_LEVEL_HIGH>,
@@ -112,6 +113,7 @@
 		#dma-cells = <1>;
 		iommus = <&smmu TEGRA186_SID_GPCDMA_0>;
 		dma-coherent;
+		dma-channel-mask = <0xfffffffe>;
 		status = "okay";
 	};
 
diff --git a/arch/arm64/boot/dts/nvidia/tegra194.dtsi b/arch/arm64/boot/dts/nvidia/tegra194.dtsi
index 28740c014f1d..fb073c459234 100644
--- a/arch/arm64/boot/dts/nvidia/tegra194.dtsi
+++ b/arch/arm64/boot/dts/nvidia/tegra194.dtsi
@@ -142,7 +142,8 @@
 			reg = <0x2600000 0x210000>;
 			resets = <&bpmp TEGRA194_RESET_GPCDMA>;
 			reset-names = "gpcdma";
-			interrupts = <GIC_SPI 76 IRQ_TYPE_LEVEL_HIGH>,
+			interrupts = <GIC_SPI 75 IRQ_TYPE_LEVEL_HIGH>,
+				     <GIC_SPI 76 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 77 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 78 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 79 IRQ_TYPE_LEVEL_HIGH>,
@@ -176,6 +177,7 @@
 			#dma-cells = <1>;
 			iommus = <&smmu TEGRA194_SID_GPCDMA_0>;
 			dma-coherent;
+			dma-channel-mask = <0xfffffffe>;
 			status = "okay";
 		};
 
diff --git a/arch/arm64/boot/dts/nvidia/tegra234.dtsi b/arch/arm64/boot/dts/nvidia/tegra234.dtsi
index 5d7df32fd159..e1165b75f708 100644
--- a/arch/arm64/boot/dts/nvidia/tegra234.dtsi
+++ b/arch/arm64/boot/dts/nvidia/tegra234.dtsi
@@ -28,7 +28,8 @@
 			reg = <0x2600000 0x210000>;
 			resets = <&bpmp TEGRA234_RESET_GPCDMA>;
 			reset-names = "gpcdma";
-			interrupts = <GIC_SPI 76 IRQ_TYPE_LEVEL_HIGH>,
+			interrupts = <GIC_SPI 75 IRQ_TYPE_LEVEL_HIGH>,
+				     <GIC_SPI 76 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 77 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 78 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 79 IRQ_TYPE_LEVEL_HIGH>,
@@ -61,6 +62,7 @@
 				     <GIC_SPI 106 IRQ_TYPE_LEVEL_HIGH>;
 			#dma-cells = <1>;
 			iommus = <&smmu_niso0 TEGRA234_SID_GPCDMA>;
+			dma-channel-mask = <0xfffffffe>;
 			dma-coherent;
 		};
 
-- 
2.17.1

[PATCH v4 3/3] dmaengine: tegra: Add support for dma-channel-mask

[Akhil R]

Add support for dma-channel-mask so that only the specified channels
are used. This helps to reserve some channels for the firmware.

This was initially achieved by limiting the channel number to 31 in
the driver and adjusting the register address to skip channel0 which
was reserved for a firmware. This is wrong and does not align with
the hardware.

Now, with this change, the driver can align more to the actual hardware
which has 32 channels. But this implies that there will be a break in the
ABI and the device tree need to be updated along with this change for the
driver to pickup the right interrupt corresponding to the channel

Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Link: https://lore.kernel.org/all/Y2EFoG1H9YpfxRjs@orome/
Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
---
 drivers/dma/tegra186-gpc-dma.c | 37 +++++++++++++++++++++++++++-------
 1 file changed, 30 insertions(+), 7 deletions(-)

diff --git a/drivers/dma/tegra186-gpc-dma.c b/drivers/dma/tegra186-gpc-dma.c
index fa9bda4a2bc6..1d1180db6d4e 100644
--- a/drivers/dma/tegra186-gpc-dma.c
+++ b/drivers/dma/tegra186-gpc-dma.c
@@ -161,7 +161,10 @@
 #define TEGRA_GPCDMA_BURST_COMPLETION_TIMEOUT	5000 /* 5 msec */
 
 /* Channel base address offset from GPCDMA base address */
-#define TEGRA_GPCDMA_CHANNEL_BASE_ADD_OFFSET	0x20000
+#define TEGRA_GPCDMA_CHANNEL_BASE_ADDR_OFFSET	0x10000
+
+/* Default channel mask reserving channel0 */
+#define TEGRA_GPCDMA_DEFAULT_CHANNEL_MASK	0xfffffffe
 
 struct tegra_dma;
 struct tegra_dma_channel;
@@ -246,6 +249,7 @@ struct tegra_dma {
 	const struct tegra_dma_chip_data *chip_data;
 	unsigned long sid_m2d_reserved;
 	unsigned long sid_d2m_reserved;
+	u32 chan_mask;
 	void __iomem *base_addr;
 	struct device *dev;
 	struct dma_device dma_dev;
@@ -1288,7 +1292,7 @@ static struct dma_chan *tegra_dma_of_xlate(struct of_phandle_args *dma_spec,
 }
 
 static const struct tegra_dma_chip_data tegra186_dma_chip_data = {
-	.nr_channels = 31,
+	.nr_channels = 32,
 	.channel_reg_size = SZ_64K,
 	.max_dma_count = SZ_1G,
 	.hw_support_pause = false,
@@ -1296,7 +1300,7 @@ static const struct tegra_dma_chip_data tegra186_dma_chip_data = {
 };
 
 static const struct tegra_dma_chip_data tegra194_dma_chip_data = {
-	.nr_channels = 31,
+	.nr_channels = 32,
 	.channel_reg_size = SZ_64K,
 	.max_dma_count = SZ_1G,
 	.hw_support_pause = true,
@@ -1304,7 +1308,7 @@ static const struct tegra_dma_chip_data tegra194_dma_chip_data = {
 };
 
 static const struct tegra_dma_chip_data tegra234_dma_chip_data = {
-	.nr_channels = 31,
+	.nr_channels = 32,
 	.channel_reg_size = SZ_64K,
 	.max_dma_count = SZ_1G,
 	.hw_support_pause = true,
@@ -1380,15 +1384,28 @@ static int tegra_dma_probe(struct platform_device *pdev)
 	}
 	stream_id = iommu_spec->ids[0] & 0xffff;
 
+	ret = device_property_read_u32(&pdev->dev, "dma-channel-mask",
+				       &tdma->chan_mask);
+	if (ret) {
+		dev_warn(&pdev->dev,
+			 "Missing dma-channel-mask property, using default channel mask %#x\n",
+			 TEGRA_GPCDMA_DEFAULT_CHANNEL_MASK);
+		tdma->chan_mask = TEGRA_GPCDMA_DEFAULT_CHANNEL_MASK;
+	}
+
 	INIT_LIST_HEAD(&tdma->dma_dev.channels);
 	for (i = 0; i < cdata->nr_channels; i++) {
 		struct tegra_dma_channel *tdc = &tdma->channels[i];
 
+		/* Check for channel mask */
+		if (!(tdma->chan_mask & BIT(i)))
+			continue;
+
 		tdc->irq = platform_get_irq(pdev, i);
 		if (tdc->irq < 0)
 			return tdc->irq;
 
-		tdc->chan_base_offset = TEGRA_GPCDMA_CHANNEL_BASE_ADD_OFFSET +
+		tdc->chan_base_offset = TEGRA_GPCDMA_CHANNEL_BASE_ADDR_OFFSET +
 					i * cdata->channel_reg_size;
 		snprintf(tdc->name, sizeof(tdc->name), "gpcdma.%d", i);
 		tdc->tdma = tdma;
@@ -1449,8 +1466,8 @@ static int tegra_dma_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	dev_info(&pdev->dev, "GPC DMA driver register %d channels\n",
-		 cdata->nr_channels);
+	dev_info(&pdev->dev, "GPC DMA driver register %lu channels\n",
+		 hweight_long(tdma->chan_mask));
 
 	return 0;
 }
@@ -1473,6 +1490,9 @@ static int __maybe_unused tegra_dma_pm_suspend(struct device *dev)
 	for (i = 0; i < tdma->chip_data->nr_channels; i++) {
 		struct tegra_dma_channel *tdc = &tdma->channels[i];
 
+		if (!(tdma->chan_mask & BIT(i)))
+			continue;
+
 		if (tdc->dma_desc) {
 			dev_err(tdma->dev, "channel %u busy\n", i);
 			return -EBUSY;
@@ -1492,6 +1512,9 @@ static int __maybe_unused tegra_dma_pm_resume(struct device *dev)
 	for (i = 0; i < tdma->chip_data->nr_channels; i++) {
 		struct tegra_dma_channel *tdc = &tdma->channels[i];
 
+		if (!(tdma->chan_mask & BIT(i)))
+			continue;
+
 		tegra_dma_program_sid(tdc, tdc->stream_id);
 	}
 
-- 
2.17.1

Re: [PATCH v4 0/3] Tegra GPCDMA: dma-channel-mask support

[Vinod Koul]

On 10-11-22, 22:47, Akhil R wrote:
> Read dma-channel-mask from device tree and register only the
> specified channels. This is useful to reserve some channels for the
> firmware.
> 
> Also update the channel number and interrupts to include all 32
> channels. The current DT bindings has only 31 interrupts which is wrong
> and doesn't align with the hardware. This was done to reserve channel0
> for the firmware. Now with this change, the driver can align more to the
> actual hardware. but this implies that there will be a breakage in the
> ABI and device tree must be updated along with the driver change
> for it to pickup the right interrupt corresponding to the channel.
> 
> This breakage is okay right now because GPC DMA was introduced on
> Tegra186 and the DT bindings were added in 5.19. Any products released
> with this IP were released with kernels prior to 5.19 and bindings that
> were never in-tree. Any of those products that are supported upstream we
> know have replaceable DTB images (i.e. by default they are flashed at the
> same time as the kernel image).

Applied 1 & 3, thanks

-- 
~Vinod

Re: [PATCH v4 2/3] arm64: tegra: Add dma-channel-mask in GPCDMA node

[Thierry Reding]

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On Thu, Nov 10, 2022 at 10:47:47PM +0530, Akhil R wrote:
> Add dma-channel-mask property in Tegra GPCDMA device tree node.
> 
> The property would help to specify the channels to be used in
> kernel and reserve few for the firmware. This was previously
> achieved by limiting the channel number to 31 in the driver.
> This is wrong and does not align with the hardware. Correct this
> and update the interrupts property to list all 32 interrupts.
> 
> Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
> ---
>  arch/arm64/boot/dts/nvidia/tegra186.dtsi | 4 +++-
>  arch/arm64/boot/dts/nvidia/tegra194.dtsi | 4 +++-
>  arch/arm64/boot/dts/nvidia/tegra234.dtsi | 4 +++-
>  3 files changed, 9 insertions(+), 3 deletions(-)

Applied, thanks.

Thierry

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